This section introduces aspects that may help facilitate a better understanding of the inventions. Accordingly, the statements of this section are to be read in this light and are not to be understood as admissions about what is prior art or what is not prior art.
Currently, a combined device composed of a coupler and a circulator is usually used in the communication technology. The circulator is a multi-port device in which transmission of electromagnetic waves can only be unidirectionally circulated, taking a three-port ({circle around (1)}port, {circle around (2)}port and {circle around (3)}port) circulator as an example, signals can only be transmitted along a forward direction, that is {circle around (1)}port→{circle around (2)}port→{circle around (3)}port→{circle around (1)}port, the transmission of the signals along a reverse direction is isolated. In modern radar systems and multichannel microwave communication systems, a device with unidirectional circulation performance is used. For example, a circulator is usually used as a duplexer in a radar system in which a transceiver device shares one antenna. In the multichannel microwave communication system, the circulator may be used to isolate signals having different frequencies.
The principle of the circulator still lies in anisotropic characteristics of the ferrite material under a bias magnetic field. Microwave structures are divided into a microstrip type, a waveguide type, a stripline type and a coaxial type, and a microstrip three-port circulator is most used, the microstrip three-port circulator uses a ferrite material as a dielectric, makes a conductive strip structure on the ferrite material, will have a circulation performance under a applied constant magnetic field. If the direction of the bias magnetic field is changed, the direction of circulation will be changed.
However, currently, power loss easily occurs on the combined device composed of the coupler and the circulator, and because transmission lines are used to match the coupler and the circulator, unnecessary loss, such as loss at total reflection and insertion loss, and additional cost are generated. Therefore, in order to eliminate these unnecessary losses and cost, it would be desirable for the coupler and the circulator to be unified and integrated.
In view of the above problems, inventors of the present disclosure provide an integral communication device integrating a coupler and a circulator.